In the field of extremely high temperature tolerant materials it is known to use ceramic compounds combined with varying materials to transport high temperature fluids. For example, U.S. Pat. No. 2,405,075 that issued on Nov. 27, 1943 to Vollrath discloses a gas impervious ceramic tube capable of tolerating fluids reaching temperatures up to one-thousand five hundred degrees Fahrenheit (1,500° F.) (815.6° C.) for thermocouple and temperature monitoring purposes. U.S. Pat. No. 4,642,864 that issued on Feb. 17, 1987 to Metcalf et al. also discloses use of a ceramic tube with a circumferentially disposed metal sleeve that is bonded to the ceramic tube with a ceramic bonding material including 70% aluminum oxide and 25% silicon oxide. This ceramic tube having a metal sleeve is capable of tolerating high-temperature fluids passing over the metal tube while a heat absorbing fluid passes through the interior ceramic tube. The ceramic-metal tube also provides thermal expansion stability at the metal-ceramic bond. More recently, U.S. Pat. No. 5,881,775 that issued on Mar. 16, 1999 to Owen et al. discloses a heat exchanger ceramic core tube for transporting high-temperature fluids. The ceramic tube is wrapped with a circumferentially extending, reinforcing material impregnated with a slurry of ceramic particles to protect against explosive displacement of portions of the ceramic core tube in the event of a catastrophic failure of the tube.
These disclosures confront the many difficulties of integrating high-temperature tolerant ceramic materials with metal components, wherein the ceramic and metal have substantially different coefficients of thermal expansion and likewise different responses to varying mechanical, chemical and other stresses common to extreme environment heat exchangers. Heat exchangers require precise dimensions of various components. For example, for consistent rates of heat transfer, thicknesses of extremely hot fluid containing conduits and other heat transfer surfaces must be manufactured to precise tolerances. Machining of such extreme environment heat exchanger components becomes exceptionally challenging when it is necessary to extract heat from fluids reaching 3,000° F. (1,650° C.).
Therefore, there is a need for an improved extreme environment heat exchanger that overcomes the limitations of the prior art.